scholarly journals Kinetics of Fertilization in the Sea Urchin Strongylocentrotus franciscanus: Interaction of Gamete Dilution, Age, and Contact Time

1991 ◽  
Vol 181 (3) ◽  
pp. 371-378 ◽  
Author(s):  
D. R. Levitan ◽  
M. A. Sewell ◽  
F. S. Chia
Keyword(s):  
Sea Urchin ◽  
Contact Time ◽  
Strongylocentrotus Franciscanus ◽  
Kinetics Of

scholarly journals Modified/Unmodified Nanoparticle Adsorbents of Cellulose Origin With High Adsorptive Potential for Removal of Pb(II) From Aqueous Solution

2017 ◽  
Vol 13 (27) ◽  
pp. 425
Author(s):  
Azeh Yakubu ◽  
Gabriel Ademola Olatunji ◽  
Folahan Amoo Adekola
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Contact Time ◽  
Adsorption Process ◽  
Correlation Coefficients ◽  
Solution Temperature ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Kinetics Of Adsorption ◽  
Kinetics Of

This investigation was conducted to evaluate the adsorption capacity of nanoparticles of cellulose origin. Nanoparticles were synthesized by acid hydrolysis of microcrystalline cellulose/cellulose acetate using 64% H3PO4 and characterized using FTIR, XRD, TGA-DTGA, BET and SEM analysis. Adsorption kinetics of Pb (II) ions in aqueous solution was investigated and the effect of initial concentration, pH, time, adsorbent dosage and solution temperature. The results showed that adsorption increased with increasing concentration with removal efficiencies of 60% and 92.99% for Azeh2 and Azeh10 respectively for initial lead concentration of 3 mg/g. The effects of contact time showed that adsorption maximum was attained within 24h of contact time. The maximum adsorption capacity and removal efficiency were achieved at pH6. Small dose of adsorbent had better performance. The kinetics of adsorption was best described by the pseudo-second-Order model while the adsorption mechanism was chemisorption and pore diffusion based on intra-particle diffusion model. The isotherm model was Freundlich. Though, all tested isotherm models relatively showed good correlation coefficients ranging from 0.969-1.000. The adsorption process was exothermic for Azeh-TDI, with a negative value of -12.812 X 103 KJ/mol. This indicates that the adsorption process for Pb by Azeh-TDI was spontaneous. Adsorption by Azeh2 was endothermic in nature.

Kinetics of Fertilization in the Sea Urchin: A Comparison of Methods

1970 ◽  
Vol 52 (2) ◽  
pp. 455-468
Author(s):  
R. PRESLEY ◽  
P. F. BAKER
Keyword(s):  
Sea Urchin ◽  
Uranyl Nitrate ◽  
Sea Water ◽  
Fertilization Rate ◽  
The Other ◽  
Jelly Coat ◽  
Cortical Responses ◽  
Direct Counting ◽  
Further Development ◽  
Kinetics Of

1. A method is described for the direct counting of male pronuclei in recently fertilized sea-urchin eggs. 2. Using this method, fertilization rate determinations were made to compare 30% artificial sea water (A.S.W.), isotonic KCl, sea water containing lauryl sulphate, calcium-free and magnesium-free A.S.W. containing EDTA, and sea water containing uranyl nitrate, as agents blocking fertilization but permitting further development of previously fertilized eggs. 3. 30% A.S.W. was found to be less satisfactory than the other agents, lacking instant effect, and tending to promote polyspermy. The other agents all gave sigmoid rate curves, that of uranyl nitrate lagging 15-25 sec. behind the others. 4. Evidence was found that uranyl nitrate acts at a later stage in fertilization than the other agents. 5. Sigmoid rate curves were found, except with 30% A.S.W., when eggs with the bulk of the jelly coat removed, and nicotine-treated eggs, were fertilized. 6. Analysis of sperm distribution among eggs from samples fertilized for more than 40 sec. confirmed that re-fertilization takes place at a lower rate than primary fertilization. 7. The processes blocked by KCl and uranyl nitrate were found to precede the cortical responses to fertilization, and the termination of nicotine sensitivity.

scholarly journals Use of Oak Fragments during the Aging of Red Wines. Effect on the Phenolic, Aromatic, and Sensory Composition of Wines as a Function of the Contact Time with the Wood

Beverages ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 102 ◽  
Author(s):  
Pilar Rubio-Bretón ◽  
Teresa Garde-Cerdán ◽  
Juana Martínez
Keyword(s):  
Volatile Compounds ◽  
Contact Time ◽  
Sensory Level ◽  
Red Wines ◽  
Extraction Kinetics ◽  
Organoleptic Characteristics ◽  
Oak Barrels ◽  
Wine Aging ◽  
Kinetics Of ◽  
Over Time

The use of oak fragments allows wine cellars to reduce costs and the length of wine aging compared to traditional aging in oak barrels in the winery. The main objective of this work was to study the effect of the use of oak fragments on the volatile, phenolic, and organoleptic characteristics of Tempranillo red wines, as a function of the contact time between the wood and the wine. The results showed important changes in the wines’ colorimetric parameters after two months of contact time. Extraction kinetics of volatile compounds from the wood was highest during the first month of contact for chips, variable for staves, and slower and continuous over time for barrels. Wines macerated with fragments showed the best quality in short periods of aging, while barrel-aged wines improved over the time they spent in the barrel. In addition, the results allowed an analytical discrimination between the wines aged with oak fragments and those aged in oak barrels, and between chips and staves, just as at the sensory level with triangular tasting tests. In conclusion, the use of oak fragments is a suitable practice for the production of red wines, which may be an appropriate option for wines destined to be aged for short periods.

Modeling batch kinetics of cesium, cobalt and strontium ions adsorption from aqueous solutions using hydrous titanium oxide

2007 ◽  
Vol 95 (7) ◽  
Author(s):  
E. Metwally ◽  
R. O. Abdel Rahman ◽  
R. R. Ayoub
Keyword(s):  
Free Energy ◽  
Aqueous Solutions ◽  
Thermodynamic Parameters ◽  
Titanium Oxide ◽  
Contact Time ◽  
Cobalt Ions ◽  
Batch Kinetics ◽  
Batch Technique ◽  
Strontium Ions ◽  
Kinetics Of

Hydrous titanium oxide was chemically synthesized and tested as adsorbent material for the removal of cesium, cobalt and strontium ions from chloride waste solutions using batch technique. The influences of pH, contact time, and temperature have been reported. The uptake of both strontium and cobalt ions was found to be greater than that of cesium and the apparent sorption capacity of each ion increases with increase in temperature. Thermodynamic parameters such as changes in Gibbs free energy (Δ

scholarly journals Activation of sea-urchin sperm motility is accompanied by an increase in the creatine kinase exchange flux

1997 ◽  
Vol 325 (2) ◽  
pp. 411-416 ◽  
Author(s):  
Ferdi A. van DORSTEN ◽  
Markus WYSS ◽  
Theo WALLIMANN ◽  
Klaas NICOLAY
Keyword(s):  
Creatine Kinase ◽  
Sea Urchin ◽  
Magnetization Transfer ◽  
Order Rate Constant ◽  
Phosphate Transport ◽  
High Energy ◽  
Sperm Activation ◽  
Kinetics Of ◽  
Sea Urchin Sperm ◽  
Exchange Flux

The kinetics of the creatine kinase (CK) reaction were studied in suspensions of quiescent and active, intact sea-urchin spermatozoa in artificial seawater, using 31P-NMR magnetization transfer. In inactive sperm, no CK-mediated exchange flux was detected, whereas in activated motile sperm, the forward pseudo-first-order rate constant was 0.13±0.04 s-1 at 10 °C, corresponding to a steady-state CK flux of 3.1±0.5 mM·s-1. Intracellular pH shifted from 6.6±0.1 to 7.6±0.1 upon activation. The phosphocreatine (PCr)/ATP and PCr/Pi ratios were only marginally reduced in activated sperm, whereas the estimated cytosolic free ADP concentration increased remarkably from 9 μM in quiescent, to 114 μM in activated spermatozoa. The elevation of CK flux upon sperm activation is discussed in the light of the proposition that in sea-urchin spermatozoa, which are fuelled entirely by oxidative phosphorylation, high-energy phosphate transport is mediated by a ‘CK/PCr shuttle‘.

The kinetics of autolysis in osmotically stressed sea urchin eggs

1992 ◽  
Vol 203 ◽  
pp. 493-501 ◽  
Author(s):  
Robert J. Williams ◽  
Tsuneo Takahashi ◽  
Allen G. Hirsh
Keyword(s):  
Sea Urchin ◽  
Sea Urchin Eggs ◽  
Kinetics Of

scholarly journals Study of Kinetics and Adsorption Isotherm of Methylene Blue Dye using Tannin Gel from Ceriops tagal

2020 ◽  
Vol 23 (10) ◽  
pp. 370-376
Author(s):  
Thamrin Azis ◽  
La Ode Ahmad ◽  
Keke Awaliyah ◽  
Laode Abdul Kadir
Keyword(s):  
Methylene Blue ◽  
Adsorption Capacity ◽  
Adsorption Kinetics ◽  
Contact Time ◽  
Adsorption Process ◽  
Blue Dye ◽  
Maximum Adsorption Capacity ◽  
Methylene Blue Dye ◽  
Ceriops Tagal ◽  
Kinetics Of

Research on the equilibrium and adsorption kinetics of methylene blue dye using tannin gel from the Tingi tree (Ceriops tagal) has been carried out. This study aims to determine the capacity and adsorption kinetics of tannin gel against methylene blue dye. Several parameters, such as the effect of contact time, pH, and methylene blue dye concentration on adsorption, were also studied. Based on the research results, the optimum adsorption process is a contact time of 30 minutes and a pH of 7. The adsorption capacity increased to a concentration of 80 mg/L with a maximum adsorption capacity (qm) of 49.261 mg/g. The adsorption process follows the pseudo-second-order adsorption kinetics model and the Langmuir isotherm model.

scholarly journals STUDY ON THE ADSORPTION PROPERTIES OF NOVEL CALIX[6]ARENE POLYMERS FOR HEAVY METAL CATIONS

2012 ◽  
Vol 12 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Susy Yunita Prabawati ◽  
Jumina Jumina ◽  
Sri Juari Santosa ◽  
Mustofa Mustofa ◽  
Keisuke Ohto
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Adsorption Kinetics ◽  
Contact Time ◽  
Adsorption Process ◽  
Metal Cations ◽  
Kinetics Model ◽  
Batch Method ◽  
Heavy Metal Cations ◽  
Kinetics Of

A research has been conducted to investigate the capability of a series of novel calix[6]arenes-based polymers: poly-monoallyloxycalix[6]arene (2a), poly-monoallyloxypenta-estercalix[6]arene (2b) and poly-monoallyloxypenta-acidcalix[6]arene (2c) for trapping of heavy metal cations such as Cd(II), Cu(II) and Cr(III). The existence of active hydroxy group (-OH) and with a tunnel-like structure of the polymers, caused the polymers can be used as adsorbents for heavy metals. The adsorption process was carried out in batch method in the variation of acidity (pH), contact time and initial concentration of metal ions. The results showed that the amount of adsorbed metal increased with the increasing of the pH of metal solution. For these three polymers, the amount of metal ions Cd(II), Cu(II) and Cr(III) adsorbed was optimum at pH 7, 6 and 5 respectively. The optimum contact time for Cd(II) and Cu(II) was 120 min, while that for Cr(III) was 60 min. Study of the adsorption kinetics showed that the adsorption of Cd(II), Cu(II) and Cr(III) using polymer 2a followed kinetics model of Ho. For adsorbent 2b and 2c, the adsorption kinetics of Cd(II) and Cr(III) also followed kinetics model of Ho while for the Cu(II) followed Lagergren kinetic models. Isothermal studies showed that the adsorption of metal ions on all adsorbents tend to follow the Langmuir isotherm. The adsorption energies of the three adsorbents were higher than 23 kJ/mole and polymer 2c has the largest adsorption capacity for Cr(III).

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